1. Field of the Invention
The present invention relates to a method for fabricating a conductive layer, and more particularly, to a method for fabricating a conductive layer in a liquid crystal display.
2. Description of Related Art
Nowadays, multimedia technology has been well developed, which is due to the development of semiconductor devices and display apparatuses. As for displays, liquid crystal displays (LCDs) having advantages such as high image display quality, good space utilization, low power consumption and no radiation have gradually become the mainstream products of the market. In general, a liquid crystal display (LCD) mainly includes a thin film transistor TFT) array substrate, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. Herein, a thin film transistor array is formed by a plurality of thin film transistors and other related peripheral circuits. In practice, the gate, the source, the drain and the peripheral circuits in a thin film transistor are formed by patterning metal materials.
For example, in a thin film transistor array substrate, the gate and the scan line in a thin film transistor are formed by the same patterning process. Prior to the formation of the gate and the scan line, a metal layer is formed on a substrate by a physical vapor deposition (PVD) process. Next, a patterning process is performed to the metal layer to form the gate and the scan line. The patterning process includes steps such as photoresist coating, exposure, lithography, and etching. Therefore, the overall fabrication process is complicated. Further, due to the related materials such as etchants and photomasks and the equipment required for the fabrication, the manufacturing costs cannot be effectively lowered.
In addition, forming a conductive line of a multi-layer structure requires multiple physical vapor deposition processes and an etching process. A common example is a nickel/copper double-layer structure. Since a physical vapor deposition process requires an expensive vacuum deposition equipment, a suitable etchant must be developed for the etching process. For example, in practice, it is not easy to find a suitable etchant that etches copper and nickel at the same time. Therefore, the costs for developing such an etchant cannot be easily reduced.